1. Field of the Invention
This invention relates generally to improvements in carpet razor knives, and more particularly to an adjustable guide means and consequently to an improved method for using such knives in trimming the salvage edge of carpeting.
2. Description of the Prior Art
Carpet razor knives are used by carpet layers for general installation work and consequently are well known. A typical carpet has a nap portion and a backing portion. The nap portion is generally embedded in and permanently secured to the backing portion.
When carpeting is being installed, a problem routinely encountered involves seaming the border areas where two rooms or living areas meet. The two disparate carpets should meet in an optimal manner so that the juxtaposition line formed by the two carpets is not readily apparent to the casual observer.
The conventional method of producing the desired seam, known as the double cut method, is as follows. The abutting edge of one of the carpets is made to overly the abutting edge of the underlying carpet. The amount of overlap might be for example an inch or two. A carpet razor knife is then used to cut both carpet protions at the same time, by guiding the knife on a straight line through the medial region of the overlapping area. Since this cut is made when the nap portion of each carpet is facing upwardly i.e., toward the razor, shear tips will be produced. In other words, on both of the carpets, the nap immediately adjacent the cut will be shorter than the nap spaced apart from the cut.
It is therefore necessary to trim the salvage edge off of both of the carpets to thereby remove that portion of the nap cut by the razor and having a short length in consequence thereof.
There are two known methods for trimming the salvage edge. In both methods, the salvage edge (that portion of the carpet carrying short nap), is trimmed by folding the carpet over upon itself, to expose the backing. Since the double cut has produced mating edges, spoiled only by the short nap adjacent the cut line, the salvage edge must be trimmed along a straight line to preserve the substantially perfect seam produced by the double cut. The first of the two known methods, therefore, incorporates the use of a straight edge tool, preferably of four to six feet in length. The straight edge is carefully placed in parallel alignment with the salvage edge to be removed, and a carpet razor knife is used to make the cut, using the straight edge of a guide. The second known method contemplates snapping a conventional chalk line to produce a straight chalk line in spaced apart parallel alignment with the salvage edge to be trimmed, followed by, of course, cutting along the line with the carpet razor knife.
It should be noted that a considerable amount of skill is needed to properly align either the straight edge of the chalk line and to make the cut along the line so defined. Also, due to the level of skill required, it will also be appreciated that the time required to trim a salvage edge by either of the two known methods is substantial. Morever, since neither the straight edge or the chaulk line can be placed close to the salvage edge to be trimmed, excess amounts of carpeting must be trimmed off.
Both of the known methods suffer from yet another problem. The act of folding the carpet over upon itself introduces a bowed effect into the carpeting. Thus, any attempt to cut along a straight line will fail, and a substantially perfect seam cannot be made. The seemingly straight line, in other words will actually follow an arcuate or curved path. Thus, the substantially perfect seam that had been produced by the double cut is lost in the process of trimming the short nap carrying salvage edge.